Portable double-ended grounding loop resistance testing device

Abstract

This application provides a portable double-ended grounding loop resistance testing device, belonging to the field of electrical variable measurement technology. It includes a shunt-compensated loop resistance tester, a power supply, an operation panel, a safety box, and a lead wire winding mechanism. The shunt-compensated loop resistance tester is connected to the current sampling terminal via sampling leads, which are wound around the lead wire winding mechanism. The lead wire winding mechanism includes a drive unit, a synchronous transmission mechanism, and two winding rollers, which are connected to the drive unit via the synchronous transmission mechanism. This application simplifies the on-site operation process and improves the portability and transport reliability of the device by integrating and synchronously winding and storing the two sampling leads. The synchronous transmission mechanism drives the two winding rollers to operate synchronously, ensuring that the exposed lengths of the two sampling leads remain consistent, maintaining the symmetry of signal attenuation and power frequency interference pickup in the two sampling channels, and effectively ensuring the accuracy of loop resistance measurement in double-ended grounding scenarios.

Description

Technical Field

[0001] This application relates to the field of electrical variable measurement technology, specifically to a portable double-ended grounding loop resistance testing device. Background Technology

[0002] The double-ended grounding loop resistance tester is a specialized testing device used in power system maintenance operations to measure the resistance of conductive loops in power components such as high-voltage circuit breakers and GIS equipment.

[0003] Existing dual-terminal grounding loop resistance testing devices typically use independent external sampling leads, which are not only inconvenient to carry but also require manual selection or preparation of cables of appropriate length based on the working distance during field operations. After completion, these cables must be manually stored, making the process cumbersome. Furthermore, the distance between the grounding points at both ends of the tested equipment is not fixed during field operations, making it difficult for operators to ensure that the exposed lengths of the two cables remain consistent. Since shunt sampling transmits weak analog signals, differences in exposed length can lead to asymmetry in the amount of power frequency electromagnetic interference picked up and the degree of signal attenuation between the two cables, disrupting the proportional consistency of the two sampling channels and causing deviations in the loop resistance measurement results. This deviation has a more significant impact on measurement accuracy, especially in strong electromagnetic environments.

[0004] In summary, existing double-ended grounding loop resistance testing devices suffer from technical problems such as inconvenient sampling lead retraction and the difficulty in maintaining consistent exposed lengths of the two leads, which in turn affects measurement accuracy. Utility Model Content

[0005] This application addresses the problems existing in the prior art by providing a portable and more accurate double-ended grounding loop resistance testing device.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: This application provides a portable double-ended grounding loop resistance testing device, which includes a shunt-compensated loop resistance tester, a power supply, and an operation panel; the shunt-compensated loop resistance tester is connected to the power supply and the operation panel respectively; It also includes a safety box and a lead wire take-up and retraction mechanism; the shunt-compensated loop resistance tester, power supply, operation panel and the lead wire take-up and retraction mechanism are all configured in the safety box; The shunt-compensated loop resistance tester is connected to the current sampling terminal via a sampling lead; the sampling lead is wound around the lead take-up and release mechanism. The lead wire take-up and untake-down mechanism is equipped with a drive unit, a synchronous transmission mechanism and two take-up rollers, and the two take-up rollers are connected to the drive unit through the synchronous transmission mechanism. The two output ends of the synchronous transmission mechanism rotate in opposite directions, and the winding directions of the sampling leads on the two take-up rollers are opposite.

[0007] Optionally, the synchronous transmission mechanism includes a transmission chain, a driving sprocket, a driven sprocket, a driving gear, and a driven gear; the two take-up rollers include a first take-up roller and a second take-up roller; The output end of the drive unit is connected to the drive sprocket; The drive chain spans the driving sprocket and the driven sprocket, and the driven sprocket is coaxially and fixedly connected to the first take-up roller; The drive sprocket and the drive gear are coaxially and fixedly connected; The driving gear meshes with the driven gear, and the driven gear is coaxially fixed to the second take-up roller.

[0008] Optionally, both take-up rollers are cable reels with built-in slip rings; The lead-out ends of the two take-up rollers are both connected to the current sampling interface of the shunt-compensated loop resistance tester. The terminals of the two take-up rollers are respectively connected to the corresponding sampling leads.

[0009] Optionally, the lead wire take-up and untake-down mechanism is further provided with a guide structure, and each take-up roller is configured with an independent guide structure; The guiding structure includes a guide rod and a guide ring; the guide ring is fixed on the guide rod, and each sampling lead passes through the corresponding guide ring; The two guiding structures are staggered along the transport direction of the sampling lead.

[0010] Optionally, the safety box includes an upper cover and a lower box body; the upper cover is hinged to the lower box body, and the safety box has a latch on the switch side; The lower housing has a T-shaped partition inside, and the safety box is divided into a first cavity, a second cavity, and a third cavity by the partition; The first cavity is equipped with the shunt-compensated loop resistance tester; The second cavity is equipped with the lead wire take-up and delivery mechanism; The power supply is installed in the third cavity.

[0011] Optionally, the partition can be a metal partition or a non-metal partition; When the partition is a non-metallic partition, a metal layer is provided on the surface of the partition.

[0012] Optionally, the lower housing is provided with a handle on the front side, and the lower housing is provided with reinforcing ribs, lead wire outlets and power interfaces.

[0013] Optionally, the operation panel may include one or more combinations of a display, buttons, switches, and expansion interfaces.

[0014] Optionally, the back of the operation panel is provided with a shielding layer.

[0015] Optionally, the current sampling terminal is a current clamp; The current clamp is held in place on the grounding wire of the object being tested.

[0016] Compared with the prior art, this application has the following advantages: This application integrates a lead wire take-up and take-up mechanism within the safety box to achieve integrated storage and synchronous take-up and take-up of the two sampling leads, simplifying the on-site operation process and improving the portability and transport reliability of the device. By driving the two take-up rollers to operate synchronously through a synchronous transmission mechanism, the exposed length of the two sampling leads is always kept consistent, maintaining the symmetry of signal attenuation and power frequency interference pickup of the two sampling channels, and effectively ensuring the accuracy of loop resistance measurement in double-ended grounding scenarios. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a perspective view of the device in a specific embodiment of this application; Figure 2 This is a top view of the operation panel in a specific embodiment of this application; Figure 3 This is a perspective view of the operation panel from the back in a specific embodiment of this application; Figure 4 This is a top view of the lower housing in a specific embodiment of this application; Figure 5 This is a device system diagram in a specific embodiment of this application; Figure 6 This is a schematic diagram of current sampling in a specific embodiment of this application; Figure 7 This is a top view of the lead wire take-up and release mechanism in a specific embodiment of this application; Figure 8 This is a perspective view of the lead wire take-up and release mechanism in a specific embodiment of this application.

[0019] In the picture: 1. Safety box; 101. Lower box body; 102. Top cover; 103. Handle; 104. Lock; 105. Power interface; 106. Lead wire outlet; 107. First cavity; 108. Second cavity; 109. Third cavity; 110. Partition. 2. Operation panel, 201. Display area, 202. Expansion interface area, 203. Button area, 204. Speaker, 205. Main switch, 206. Shielding layer; 3. Lead wire take-up and unwinding mechanism, 301, first take-up roller, 302, second take-up roller, 303, driven sprocket, 304, driving sprocket, 305, transmission chain, 306, driven gear, 307, driving gear, 308, first guide rod, 309, first guide ring, 310, second guide rod, 311, second guide ring, 312, output shaft, 313, lead wire end; 4. Shunt-compensated loop resistance tester; 5. Power supply; 6. Sampling leads; 7. Current clamp. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] In the description of this application, it should be understood that the relative relationship indicated by terms such as "upper" and "lower" is based on the position shown in the drawings, and is used for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, and therefore should not be construed as a limitation of this application.

[0023] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0024] In the description of this application, "multiple" means two or more, unless otherwise expressly and specifically defined.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0026] It is worth noting that, unless otherwise specified, the methods used in this application are all conventional methods; and the raw materials and equipment used are all conventional commercially available products, and their sources are not specifically limited.

[0027] like Figure 1 and Figure 5 As shown, the portable double-ended grounding loop resistance test device provided in this embodiment is integrated inside the safety box 1 and mainly includes a shunt compensation loop resistance tester 4, a power supply 5, an operation panel 2, and a lead wire winding and unwinding mechanism 3.

[0028] Among them, the shunt compensation loop resistance tester 4 is electrically connected to the power supply 5 and the operation panel 2 respectively. The power supply 5 provides working power to all modules of the whole machine. The operation panel 2 is used to realize test parameter setting, measurement data display and human-machine interaction. The lead wire winding and unwinding mechanism 3 is used to realize the synchronous winding and unwinding and storage of the two sampling leads 6.

[0029] like Figure 1 and Figure 4 As shown, the safety box 1 adopts a portable rigid protective box structure, including an upper cover 102 and a lower box 101 that are hinged to each other, and a latch 104 is provided on the opening and closing side of the box. After the upper cover 102 and the lower box 101 are latched, a closed protective space can be formed, which has the ability to prevent dust, splash and crush, and meets the protection requirements for outdoor transportation and substation on-site operation.

[0030] A handle 103 is located on the front center of the lower housing 101, facilitating short-distance transport by a single person. Multiple raised reinforcing ribs are installed on the outer wall of the lower housing 101 to enhance the overall structural strength and prevent deformation due to external pressure during transport, thus protecting the internal measuring components. Two lead wire outlets 106 and a power interface 105 are located on the side wall of the lower housing 101. The lead wire outlets 106 allow two sampling leads 6 to exit through the lower housing 101, and are equipped with wear-resistant protective rings at the outlets to prevent the cables from being cut by the housing wall during long-term handling. The power interface 105 is used to connect to external AC power to charge the power supply 5, and also supports continuous operation of the entire unit when plugged in. Combined with the integrated power supply 5, it meets both portability and long-term testing requirements.

[0031] The lower housing 101 is fixedly provided with a T-shaped partition 110, which divides the internal space of the housing into a first cavity 107, a second cavity 108 and a third cavity 109.

[0032] The first cavity 107 is located on one side of the enclosure and is used to install the shunt-compensated loop resistance tester 4; the second cavity 108 is located on the rear side of the enclosure and is used to install the lead wire take-up mechanism 3; the third cavity 109 is located on the other side of the enclosure and is used to fix and install the power supply 5. The three cavities are separated to avoid electromagnetic interference between the high-current power circuit, the weak signal sampling circuit and the power supply circuit, thereby improving the measurement stability in a strong electromagnetic environment. Furthermore, in this embodiment, the partition 110 can be made of metal, utilizing the electromagnetic shielding properties of metal to block interference conduction between different cavities; in other embodiments of this application, when using non-metallic partitions such as engineering plastics to achieve weight reduction, a metal shielding layer can be plated on the surface of the partition 110, which can also achieve an equivalent electromagnetic isolation effect, balancing the weight of the enclosure and the shielding performance.

[0033] like Figures 6-8 As shown, the lead wire take-up and untake-down mechanism 3 is fixedly installed on the bottom plate of the second cavity 108, and mainly includes a drive unit, a synchronous transmission mechanism, and two take-up rollers. The two take-up rollers are the first take-up roller 301 and the second take-up roller 302, respectively. Their axes are arranged in parallel, and both are rotatably supported on the bottom plate of the lower housing 101 through bearing seats at both ends, and can rotate freely around their respective axes. The shunt compensation loop resistance tester 4 is connected to the current sampling terminal through sampling leads 6. The two sampling leads 6 are respectively wound around the cylindrical surfaces of the first take-up roller 301 and the second take-up roller 302, and the winding directions of the two sampling leads 6 on the first take-up roller 301 and the second take-up roller 302 are opposite.

[0034] A synchronous transmission mechanism is connected between the drive unit and the two take-up rollers. The drive unit can be a motor, which drives the two take-up rollers to rotate simultaneously through the synchronous transmission mechanism. The two output ends of the synchronous transmission mechanism rotate in opposite directions. Combined with the opposite cable winding directions on the two take-up rollers, the two sampling leads 6 can be simultaneously extended out of the housing or simultaneously retracted into the housing, ensuring that the exposed lengths of the two cables are always strictly equal at any take-up or retraction position.

[0035] Specifically, such as Figure 7 and Figure 8 As shown, the synchronous transmission mechanism includes a transmission chain 305, a driving sprocket 304, a driven sprocket 303, a driving gear 307, and a driven gear 306. In this embodiment, the drive unit specifically employs a miniature DC geared motor, whose output shaft 312 is vertically arranged, and its output end is coaxially and fixedly connected to the driving sprocket 304. The driving sprocket 304 and the driven sprocket 303 are on the same horizontal plane, and the transmission chain 305 is tensioned and spans across the driving sprocket 304 and the driven sprocket 303, forming a closed chain drive pair. The driven sprocket 303 is coaxially and fixedly mounted on the end shaft of the first take-up roller 301. When the drive unit operates, it drives the first take-up roller 301 and the driving sprocket 304 to rotate synchronously in the same direction through chain transmission.

[0036] A drive gear 307 is coaxially fixed below the drive sprocket 304, and the drive gear 307 rotates synchronously with the output shaft 312. The drive gear 307 meshes with the driven gear 306 to form a gear transmission pair with a transmission ratio of 1:1. The driven gear 306 is coaxially fixed on the end shaft of the second take-up roller 302. During operation, the drive gear 307 rotates synchronously with the drive sprocket 304, and drives the driven gear 306 to rotate in the opposite direction through gear meshing, thereby driving the second take-up roller 302 and the first take-up roller 301 to rotate at the same speed but in opposite directions. Since the two sampling leads 6 are wound in opposite directions on the two take-up rollers, the two take-up rollers rotating synchronously in opposite directions can realize the synchronous release or synchronous retraction of the sampling leads 6, and the length of each turn is completely consistent, thereby ensuring that the exposed length of the two sampling leads 6 is always equal, eliminating the sampling signal asymmetry error caused by the length difference.

[0037] Furthermore, in this embodiment, both the first take-up roller 301 and the second take-up roller 302 are cable reels with built-in slip rings, forming an overall I-beam structure. The main body of the take-up roller is a hollow cylinder, with a cap-type conductive slip ring coaxially installed inside. The rotor side of the conductive slip ring is fixedly connected to the take-up roller cylinder and rotates synchronously with the cylinder. The terminal on the rotor side serves as the terminal of the take-up roller, and the terminals of the two take-up rollers are respectively connected to the inner ends of the corresponding sampling leads 6. The stator side of the conductive slip ring is fixedly installed on the central fixed shaft of the take-up roller, maintaining a stationary state. The stator side outlet end 313 serves as the outlet end of the take-up roller and is connected to the current sampling interface of the shunt-compensated loop resistance tester 4. Through the built-in conductive slip ring structure, the circuit remains connected during the continuous rotation of the take-up roller to wind up and unwind the cable, preventing the sampling leads 6 from twisting, bending, or even breaking as the take-up roller rotates. It also ensures continuous conduction of the cable shielding layer throughout the entire process, maintaining the power frequency anti-interference performance of the sampling circuit. The two winding rollers use conductive slip rings of the same specification and batch, and their contact resistance and signal transmission characteristics are highly consistent, which can ensure the parameter symmetry of the two sampling channels and avoid introducing additional proportional errors.

[0038] The lead wire take-up and untake-down mechanism 3 is also equipped with a guide structure, and each take-up roller is equipped with an independent guide structure. Each guide structure includes a guide rod and a guide ring. Specifically, the guide structure corresponding to the first take-up roller 301 includes a first guide rod 308 and a first guide ring 309, and the guide structure corresponding to the second take-up roller 302 includes a second guide rod 310 and a second guide ring 311. The guide rod is vertically fixed to the bottom plate of the housing, and the guide ring is fixedly installed in the middle of the guide rod. Each sampling lead wire 6 passes through the corresponding guide ring and then extends horizontally to the lead wire outlet 106 on the side wall of the housing. Figure 7As shown, the two guiding structures are staggered along the conveying direction of the sampling lead 6, which can guide and limit the two sampling leads 6 respectively, preventing the sampling leads 6 from deviating, overlapping, or slipping off from both sides of the roller; at the same time, the staggered arrangement can prevent the two cables from rubbing against each other and crossing each other during the cable exit process, improving the smoothness of take-up and release and the service life of the cables.

[0039] The shunt-compensated loop resistance tester 4 is the measurement unit of the device, which can be selected according to actual needs. One example is a four-terminal Kelvin measurement architecture, which integrates a high-current constant current source module, a main current sampling module, a voltage sampling module, and two independent shunt sampling processing modules. During operation, the high-current constant current source outputs a stable DC test current to the conductive loop of the power component under test through the main test lead. The voltage sampling module independently collects the voltage drop across the components under test. At the same time, the two shunt sampling channels are connected to the current sampling terminals at the ends through sampling leads 6 to collect the shunt current values ​​on the grounding wires at both ends of the components under test. The instrument internally performs shunt cancellation calculations to subtract the shunt component of the grounding bypass, obtaining the effective current flowing through the conductive loop of the components under test. Then, it calculates the accurate loop resistance value according to Ohm's law.

[0040] In this embodiment, the current sampling terminal is a current clamp 7, specifically a DC clamp current sensor. During testing, the current clamp 7 is clamped onto the grounding wire of the object under test, and non-contact measurement of the shunt current can be achieved without disconnecting the grounding wire, maintaining the integrity of the maintenance grounding state throughout the process.

[0041] Power supply 5 uses a rechargeable lithium battery pack with built-in charge and discharge management circuit and multi-stage voltage regulation circuit. It can provide a stable working power supply for the whole machine in outdoor sites without mains power access, meeting the power supply needs of mobile operations. At the same time, it can be charged by external mains power through power interface 105, and also supports charging while using, adapting to different on-site operation scenarios of different durations.

[0042] like Figure 2 , Figure 3As shown, the operation panel 2 is embedded in the top surface of the lower housing 101. The operation panel 2 integrates a display, buttons, switches, and expansion interfaces. The display area 201 corresponds to a display or LCD digital panel for real-time display of measurement results, test parameters, remaining battery power, and other information. The button area 203 corresponds to function buttons for operations such as test start, parameter setting, and data storage query. A speaker 204 is also located below the button area 203 for broadcasting alarm or low battery information. The main switch 205 is the power switch for the entire machine, controlling the power supply. The expansion interface area 202 corresponds to various expansion interfaces, including data transmission interfaces and printing interfaces, for exporting measurement data and connecting external devices. The back of the operation panel 2 is covered with a shielding layer 206, which shields against electromagnetic interference and blocks external power frequency electromagnetic fields from interfering with the internal electronic equipment of the lower housing 101. Together with the aforementioned partition 110, it forms a sealed first cavity 107, a second cavity 108, and a third cavity 109.

[0043] The above configuration of operation panel 2 is only an example. The specific configuration can be set according to the overall configuration of the shunt compensation loop resistance tester 4. The specific configuration can be based on the overall function settings of the shunt compensation loop resistance tester 4, or the functional components can be separated according to the factory configuration of the shunt compensation loop resistance tester 4. After the operation panel 2 integrates the above components, it is electrically connected to the corresponding interface of the shunt compensation loop resistance tester 4 through the data and power interfaces on its back.

[0044] The specific working process of this device is as follows: During on-site operation, move safety box 1 to the test point, unlock latch 104 to open top cover 102, and start the machine via main switch 205. Based on the distance between the grounding points at both ends of the device under test, control the drive unit to operate, driving two take-up rollers to rotate synchronously in opposite directions via a synchronous transmission mechanism. Personnel pull the ends of the two sampling leads 6 towards the furthest measurement position, ensuring that the two sampling leads 6 do not accumulate in the lower housing 101, and simultaneously release both sampling leads 6 to the required length. After the drive unit stops, clamp one end of the current clamp 7 onto the grounding wire of the high-voltage switch under test, then pull the other sampling lead 6 to the nearest measurement position and connect the current clamp 7. After completion, personnel return to safety box 1, connect other cables, and connect the high-current output line and voltage sampling line of the main circuit. After wiring is complete, the test can be started via operation panel 2.

[0045] During testing, because the exposed lengths of the two sampling leads 6 are strictly consistent, the power frequency interference and signal attenuation levels picked up by the two cables are highly symmetrical, and the proportional consistency of the two shunt sampling channels is effectively guaranteed. This significantly reduces measurement errors caused by the strong electromagnetic environment on site and improves the accuracy of loop resistance measurement in double-grounded scenarios. After the test is completed, the control drive unit reverses its rotation, which synchronously and neatly retracts the two sampling leads 6 into the box. No manual winding and storage is required, making the operation convenient and facilitating equipment transportation and storage.

[0046] Finally, it should be noted that the above content is only used to illustrate the technical solution of this application, and is not intended to limit the scope of protection of this application. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of this application shall not depart from the substance and scope of the technical solution of this application.

Claims

1. A portable double-ended grounding loop resistance testing device, comprising a shunt-compensated loop resistance tester, a power supply, and an operation panel; wherein the shunt-compensated loop resistance tester is connected to the power supply and the operation panel respectively; Its features are, It also includes a safety box and a lead wire take-up and retraction mechanism; the shunt-compensated loop resistance tester, power supply, operation panel and the lead wire take-up and retraction mechanism are all configured in the safety box; The shunt-compensated loop resistance tester is connected to the current sampling terminal via a sampling lead; the sampling lead is wound around the lead winding mechanism. The lead wire take-up and untake-down mechanism is equipped with a drive unit, a synchronous transmission mechanism and two take-up rollers, and the two take-up rollers are connected to the drive unit through the synchronous transmission mechanism. The two output ends of the synchronous transmission mechanism rotate in opposite directions, and the winding directions of the sampling leads on the two take-up rollers are opposite.

2. The portable double-ended grounding loop resistance testing device according to claim 1, characterized in that, The synchronous transmission mechanism includes a transmission chain, a driving sprocket, a driven sprocket, a driving gear, and a driven gear; the two take-up rollers include a first take-up roller and a second take-up roller; The output end of the drive unit is connected to the drive sprocket; The drive chain spans the drive sprocket and the driven sprocket, and the driven sprocket is coaxially and fixedly connected to the first take-up roller; The drive sprocket and the drive gear are coaxially and fixedly connected; The driving gear meshes with the driven gear, and the driven gear is coaxially fixed to the second take-up roller.

3. The portable double-ended grounding loop resistance testing device according to claim 1 or 2, characterized in that, Both of the take-up rollers are cable reels with built-in slip rings. The lead-out ends of the two take-up rollers are both connected to the current sampling interface of the shunt-compensated loop resistance tester. The terminals of the two take-up rollers are respectively connected to the corresponding sampling leads.

4. The portable double-ended grounding loop resistance testing device according to claim 1 or 2, characterized in that, The lead wire take-up and untake-down mechanism is also provided with a guide structure, and each take-up roller is equipped with an independent guide structure; The guiding structure includes a guide rod and a guide ring; the guide ring is fixed on the guide rod, and each sampling lead passes through the corresponding guide ring; The two guiding structures are staggered along the transport direction of the sampling lead.

5. The portable double-ended grounding loop resistance testing device according to claim 1, characterized in that, The safety box includes an upper cover and a lower box body; the upper cover is hinged to the lower box body, and the safety box has a latch on the switch side; The lower housing has a T-shaped partition inside, and the safety box is divided into a first cavity, a second cavity, and a third cavity by the partition; The first cavity is equipped with the shunt-compensated loop resistance tester; The second cavity is equipped with the lead wire take-up and delivery mechanism; The power supply is installed in the third cavity.

6. The portable double-ended grounding loop resistance testing device according to claim 5, characterized in that, The partition can be a metal partition or a non-metal partition; When the partition is a non-metallic partition, a metal layer is provided on the surface of the partition.

7. The portable double-ended grounding loop resistance testing device according to claim 5 or 6, characterized in that, The lower housing is provided with a handle on the front side, and is also provided with reinforcing ribs, lead wire outlets, and power interfaces.

8. The portable double-ended grounding loop resistance testing device according to claim 1, characterized in that, The control panel is equipped with one or more combinations of a display, buttons, switches, and expansion interfaces.

9. The portable double-ended grounding loop resistance testing device according to claim 1 or 8, characterized in that, The back of the control panel is equipped with a shielding layer.

10. The portable double-ended grounding loop resistance testing device according to claim 1, characterized in that, The current sampling terminal is a current clamp; The current clamp is held in place on the grounding wire of the object being tested.

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